Stabilizer combination for the rotomolding process

ABSTRACT

A process for the production of polyolefin hollow articles comprises charging the polyolefin with a stabilizer combination comprising (a) at least one compound from the group of the organic phosphites or phosphonites, (b) one or more compounds selected from the group consisting of i.) hydroxylamine derivatives and ii.) amine oxide derivatives and (c) at least one compound from the group of the hindered amine stabilizers, filling this mixture into a mold, heating this mold in an oven to above 280° C., such that the stabilized polyolefin fuses, rotating the mold around at least 2 axes, the plastic spreading to the walls, and cooling the mold while still rotating, opening it and taking the resultant hollow article out.

[0001] The present invention relates to the production of polyolefinhollow articles by the rotomolding process, the processing stabilizercombination described hereinbelow being used.

[0002] The rotomolding or rotational molding/casting process is used forthe production of fairly large plastic hollow articles which may bereinforced with glass fibres (Encyclopedia of Polymer Science andEngineering, Wiley Interscience, 1988, Vol. 14, pages 659-670). Inprinciple, this process is carried out as follows: The plastic materialis filled into one half of the mold which is then closed with the otherhalf and heated in an oven such that the fused plastic material spreadsto the walls of the mold when rotated around different axes. The hollowarticle is obtained after cooling. In this manner it is possible toproduce, for example, storage and truck tanks from HD polyethylene. Theprocess normally requires temperatures in the range above 300° C.,sometimes even above 400° C. The requirements placed on the stabilizersare therefore different from and more stringent than those, for example,of the extrusion process where the temperatures are normally not muchabove 280° C.

[0003] The use of stabilizer combinations of phosphites or phosphoniteswith sterically hindered phenols and/or sterically hindered amines(HALS) in polyolefins is known [see, inter alia, R. Gaichter, H.Müiller, “Plastics Additives Handbook”, Hanser Publishers, pages 40-71(1990)].

[0004] Hydroxylamine derivatives, such as N,N,-dialkylhydroxylamines andN,N-dibenzylhydroxylamine, are well known as useful stabilizers for avariety of polymeric substrates as is taught for example in U.S. Pat.Nos. 4,590,231, 4,668,721, 4,782,105 and, 4,876,300, the relevant partsof which are incorporated herein by reference.

[0005] U.S. Pat. Nos. 4,649,221, 4,691,015 and 4,703,073 teach the useof polyhydroxylamine compounds, hydroxylamines derived from hinderedamines and alkylated N,N-dibenzylhydroxylamine derivatives,respectively, with one or more compounds selected from the group ofphenolic antioxidants, hindered amine light stabilizers, alkylatedhydroxybenzoate light stabilizers, ultraviolet light absorbers, organicphosphorus compounds, alkaline metal salts of fatty acids andthiosynergists towards stabilizing polyolefins. U.S. Pat. No. 4,782,105discloses the use of long chain N,N-dialkylhydroxylamines for thestabilization of poly(arylene sulfides) and unsaturated elastomers.Examples are shown where long chain N,N-dialkylhydroxylamines are usedtogether with phosphite stabilizers in styrene/butadiene copolymer.

[0006] U.S. Pat. No. 4,876,300 discloses the use of long chainN,N-dialkylhydroxylamines as process stabilizers for polyolefincompositions. Examples are shown where long chainN,N-dialkylhydroxylamines are used together with phosphite stabilizersand also where they are used together with hindered amine stabilizers.

[0007] U.S. Pat. Nos. 4,590,231 and 4,668,721 disclose the use ofN,N-dibenzylhydroxylamine or other hydroxylamine derivatives togetherwith metal salts of fatty acids and phenolic antioxidants for thestabilization of polyolefin compositions. The compositions may alsocontain organic phosphorus compounds or hindered amine stabilizers.

[0008] U.S. Pat. No. 5,013,510 teaches a process for the preparation oflong-chain N,N-dialkylhydroxylamines by direct oxidation. It ismentioned that the long-chain N,N-dialkylhydroxylamines are effectivetowards stabilizing polyolefin compositions.

[0009] U.S. Pat. No. 5,596,033 discloses the stabilization ofpolypropylene fiber with a binary system of select hindered amines withthe N,N-dialkylhydroxylamine produced by the direct oxidation ofN,N-di(hydrogenated tallow)amine.

[0010] U.S. Pat. No. 5,149,774 discloses the use of hydroxylaminederivatives towards reducing color formation during the recycling ofalready discolored polyolefin resins.

[0011] U.S. Pat. Nos. 5,844,029 and 5,880,191 disclose the use ofsaturated hydrocarbon amine oxides towards the stabilization ofthermoplastic resins. It is disclosed that the thermoplasticcompositions may further contain a stabilizer or mixture of stabilizersselected from phenolic antioxidants, hindered amine light stabilizers,ultraviolet light absorbers, organic phosphorus compounds, alkalinemetal salts of fatty acids and thiosynergists. The co-use of amineoxides with other stabilizers towards stabilizing polyolefins is notexemplified.

[0012] It has now been found that the combination of hydroxylaminederivatives, together with organic phosphites or phosphonites andhindered amine stabilizers results in excellent stabilization in therotomolding process. The hollow articles prepared according to thepresent invention exhibit excellent initial color and gas fadingresistance.

[0013] Accordingly, this invention relates to a novel process for theproduction of polyolefin hollow articles, which comprises

[0014] charging the polyolefin with a stabilizer combination, comprising

[0015] (a) at least one compound from the group of the organicphosphites and phosphonites,

[0016] (b) one or more compounds selected from the group consisting of

[0017] i.) hydroxylamine derivatives and

[0018] ii.) amine oxide derivatives and

[0019] (c) at least one compound from the group of the hindered aminestabilizers,

[0020] filling this mixture into a mold, heating this mold in an oven toabove 280° C., such that the stabilized polyolefin fuses,

[0021] rotating the mold around at least 2 axes, the plastic materialspreading to the walls, cooling the mold while still rotating,

[0022] opening it, and

[0023] taking the resultant hollow article out.

[0024] Of interest is a novel process wherein component (a) is at leastone compound selected from the formulae (1), (2), (3), (4), (5), (6) and(7)

[0025] in which the indices are integral and

[0026] n is 2, 3 or 4; p is 1 or 2; q is 2 or 3; r is 4 to 12; y is 1, 2or 3; and z is 1 to 6;

[0027] A₁, if n is 2, is C₂-Cl₁₈ alkylene; C₂-Cl₁₂ alkylene interruptedby oxygen, sulfur or —NR₄—; a radical of the formula

[0028]  or phenylene;

[0029] A₁, if n is 3, is a radical of the formula —C_(r)H_(2r-1)—;

[0030] A₁, if n is 4, is

[0031] A₂ is as defined for A₁ if n is 2;

[0032] B is a direct bond, —CH₂—, —CHR₄—, —CR₁R₄—, sulfur, C₅-C₇cycloalkylidene, or cyclohexylidene which is substituted by from 1 to 4C₁-C₄ alkyl radicals in position 3, 4 and/or 5;

[0033] D₁, if p is 1, is C₁-C₄ alkyl and, if p is 2, is —CH₂OCH₂—;

[0034] D₂, if p is 1, is C₁-C₄ alkyl;

[0035] E, if y is 1, is C₁-C₁₈ alkyl, —OR₁ or halogen;

[0036] E, if y is 2, is —O—A₂—O—,

[0037] E, if y is 3, is a radical of the formula R₄C(CH₂O—)₃ orN(CH₂CH₂O—)₃;

[0038] Q is the radical of an at least z-valent alcohol or phenol, thisradical being attached via the oxygen atom to the phosphorus atom;

[0039] R₁, R₂ and R₃ independently of one another are C₁-C₁₈ alkyl whichis unsubstituted or substituted by halogen, —COOR_(4,) —CN or—CONR₄R_(4;) C₂-C₁₈alkyl interrupted by oxygen, sulfur or —NR₄—;C₇-C₉phenylalkyl; C₅-C₁₂ cycloalkyl, phenyl or naphthyl; naphthyl orphenyl substituted by halogen, 1 to 3 alkyl radicals or alkoxy radicalshaving a total of 1 to 18 carbon atoms or by C₇-C₉ phenylalkyl; or aradical of the formula

[0040]  in which m is an integer from the range 3 to 6;

[0041] R₄ is hydrogen, C₁-C₁₈ alkyl, C₅-C₁₂ cycloalkyl or C₇-C₉phenylalkyl,

[0042] R₅ and R₆ independently of one another are hydrogen, C₁-C₈ alkylor C₅-C₆ cycloalkyl,

[0043] R₇ and R_(8,) if q is 2, independently of one another areC₁-C₄alkyl or together are a 2,3-dehydropentamethylene radical; and

[0044] R₇ and R₈, if q is 3, are methyl;

[0045] R₁₄ is hydrogen, C₁-C₉ alkyl or cyclohexyl,

[0046] R₁₅ is hydrogen or methyl and, if two or more radicals R₁₄ andR₁₅ are present, these radicals are identical or different,

[0047] X and Y are each a direct bond or oxygen,

[0048] Z is a direct bond, methylene, —C(R₁₆)₂— or sulfur, and

[0049] R₁₆ is C₁-C₁₈ alkyl.

[0050] Of particular interest is a novel process wherein component (a)is at least one compound selected from the formulae (1), (2), (5) and(6), in which

[0051] n is the number 2, and y is the number 1, 2 or 3;

[0052] A₁ is C₂-C₁₈ alkylene, p-phenylene or p-biphenylene,

[0053] E, if y is 1, is C₁-C₁₈ alkyl, —OR₁ or fluorine;

[0054] E, if y is 2, is p-biphenylene,

[0055] E, if y is 3, is N(CH ₂CH₂O—)₃,

[0056] R₁, R₂ and R₃ independently of one another are C₁-C₁₈ alkyl,C₇-C₉ phenylalkyl, cyclohexyl, phenyl, or phenyl substituted by 1 to 3alkyl radicals having a total of 1 to 18 carbon atoms;

[0057] R₁₄ is hydrogen or C₁-C₉ alkyl,

[0058] R₁₅ is hydrogen or methyl;

[0059] X is a direct bond,

[0060] Y is oxygen,

[0061] Z is a direct bond or —CH(R₁₆)—, and

[0062] R₁₆ is C₁-C₄ alkyl.

[0063] Likewise of interest is a novel process wherein component (a) isat least one compound selected from the formulae (1), (2), (5) and (6),in which

[0064] n is the number 2 and y is the number 1 or 3;

[0065] A₁ is p-biphenylene,

[0066] E, if y is 1, is C₁-C₁₈ alkoxy or fluorine,

[0067] E, if y is 3, is N(CH₂CH₂O—)₃,

[0068] R₁, R₂ and R₃ independently of one another are C₁-C₁₈ alkyl, orphenyl substituted by 2 or 3 alkyl radicals having a total of 2 to 12carbon atoms;

[0069] R₁₄ is methyl or tert-butyl;

[0070] R₁₅ is hydrogen;

[0071] X is a direct bond;

[0072] Y is oxygen; and

[0073] Z is a direct bond, methylene or —CH(CH 3)—.

[0074] Particular preference is given to a process wherein component (a)is at least one compound selected from the formulae (1), (2) and (6).

[0075] Special preference is given to a process wherein component (a) isat least one compound of the formula (I)

[0076] in which

[0077] R₁₇ and R₁₈ independently of one another are hydrogen, C₁-C₈alkyl, cyclohexyl or phenyl, and

[0078] R_(19 and R) ₂₀ independently of one another are hydrogen orC₁-C₄ alkyl.

[0079] The following compounds are examples of organic phosphites andphosphonites which are particularly suitable for use in component (a) inthe novel process:

[0080] Triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkylphosphites, tris(nonylphenyl) phosphite, trilauryl phosphite,trioctadecyl phosphite, distearyl pentaerythritol diphosphite,tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168, Ciba SpecialtyChemicals Corp.), diisodecyl pentaeiythritol diphosphite,bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (formula (D)),bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite(formula (E)), bisisodecyloxy-pentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite,bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis-(2,4-di-tert-butylphenyl)4,4′-biphenylene-diphosphonite (Irgafos® P-EPQ, Ciba Specialty ChemicalsCorp., formula (H)),6-isooctyloxy-2,4,8,10-tetra-tert-butyl-dibenzo[d,f][1,3,2]dioxaphosphepin(formula (C)),6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g][1,3,2]dioxaphosphocin(formula (A)), bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite,bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite (formula (G)).

[0081] With particular preference the following phosphites andphosphonites are used in component (a) in the novel process:

[0082] Tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168, CibaSpecialty Chemicals Corp.), tris(nonylphenyl) phosphite,

[0083] Very particular preference is given to the use of the followingcompounds in component (a) in the novel process:Tris(2,4-di-tert-butylphenyl)phosphite (Irgafos® 168, Ciba SpecialtyChemicals Corp.), bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite(Irgafos ® 38, Ciba Specialty Chemicals Corp., formula (G)),bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (Ultranox® 626,GE Chemicals, formula (D)),tetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene-diphosphonite(Irgafos® P-EPQ, Ciba Specialty Chemicals Corp., formula (H)), 2,2′,2″-nitrilo[triethyltris(3,3′5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite](Irgafos® 12, Ciba Specialty Chemicals Corp., formula (B)). Ultranox®641 (GE Chemicals, formula (J)), Dover-phos® S9228 (Dover Chemicals,formula (K)) or Mark® HP10 (Adeka Argus, formula (L)).

[0084] These organic phosphites and phosphonites are known compounds;many of them are commercially available.

[0085] The organic phosphites or phosphonites of component (a) arepreferably used in amounts of about 0.01% to about 10%, in particularfrom about 0.05% to about 5%, typically from about 0.1% to about 3% byweight, based on the weight of the polyolefin hollow article to bestabilized.

[0086] The hydroxylamine derivatives of component i.) employed in thenovel process are of the formula (II)

[0087] wherein

[0088] T₁ is straight or branched chain alkyl of 1 to 36 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, aralkyl of 7 to 9 carbon atoms, orsaid aralkyl substituted by one or two alkyl of 1 to 12 carbon atoms orby one or two halogen atoms;

[0089] T₂ is hydrogen, or independently has the same meaning as T₁.

[0090] Preferance is given to a process wherein the compounds ofcomponent i.) are N,N-dihydrocarbylhydroxylamines of formula (II)wherein T₁ and T₂ are independently benzyl, ethyl, octyl, lauryl,dodecyl, tetradecyl, hexadecyl, heptadecyl or octadecyl, or wherein T₁and T₂ are each the alkyl mixture found in hydrogenated tallow amine.

[0091] Special preferance is given to a process wherein the compounds ofcomponent i.) are N,N-dihydrocarbylhydroxylamines selected from thegroup consisting of N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine,N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine,N,N-didodecylhydroxylamine, N,N-ditetradecylhydroxylamine,N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine,N-hexadecyl-N-tetradecylhydroxylamine,N-hexadecyl-N-heptadecylhydroxylamine,N-hexadecyl-N-octadecylhydroxylamine,N-heptadecyl-N-octadecylhydroxylamine, and N,N-di(hydrogenatedtallow)hydroxylamine.

[0092] Particular preference is given to a process wherein component i.)is an N,N-di(alkyl)hydroxylamine produced by the direct oxidation ofN,N-di(hydrogenated tallow)amine (Irgastab® 042, Ciba SpecialtyChemicals Corp.).

[0093] The amine oxide derivatives of component ii.) are saturatedtertiary amine oxides as represented by general formula (III):

[0094] wherein

[0095] G₁ and G₂ are independently a straight or branched chain alkyl of6 to 36 carbon atoms, aryl of 6 to 12 carbon atoms, aralkyl of 7 to 36carbon atoms, alkaryl of 7 to 36 carbon atoms, cycloalkyl of 5 to 36carbon atoms, alkcycloalkyl of 6 to 36 carbon atoms or cycloalkylalkylof 6 to 36 carbon atoms;

[0096] G₃ is a straight or branched chain alkyl of 1 to 36 carbon atoms,aryl of 6 to 12 carbon atoms, aralkyl of 7 to 36 carbon atoms, alkarylof 7 to 36 carbon atoms, cycloalkyl of 5 to 36 carbon atoms,alkcycloalkyl of 6 to 36 carbon atoms or cycloalkylalkyl of 6 to 36carbon atoms; with the proviso that at least one of G₁, G₂ and βcontains a 0 carbon-hydrogen bond; and

[0097] wherein said alkyl, aralkyl, alkaryl, cycloalkyl, alkcycloalkyland cycloalkylalkyl groups may be interuppted by one to sixteen —O—,—S—, —SO—, —SO₂—, —COO—, —OCO—, —CO—, —N₄—, —CONG₄— and —NG₄CO— groups,or wherein said alkyl, aralkyl, alkaryl, cycloalkyl, alkcycloalkyl andcycloalkylalkyl groups may be substituted by one to sixteen groupsselected from —OG₄, —SG₄, —COOG₄, —OCOG₄, —COG₄, —N(G₄)₂, —CON(G₄)₂,—NG₄COG₄ and 5- and 6-membered rings containing the—C(CH₃)(CH₂R_(x))NL(CH₂R_(x))(CH₃)C— group or wherein said alkyl,aralkyl, alkaryl, cycloalkyl, alkcycloalkyl and cycloalkylalkyl groupsare both interuppted and substituted by the groups mentioned above; and

[0098] wherein G₄ is independently hydrogen or alkyl of 1 to 8 carbonatoms;

[0099] R_(x) is hydrogen or methyl, preferably hydrogen;

[0100] L is a C₁₋₃₀ straight or branched chain alkyl moiety, a —C(O)Rmoiety wherein R is a C₁₋₃₀ straight or branched chain alkyl group, or a—OR moiety wherein R is a C₁₋₃₀ straight or branched chain alkyl group;and

[0101] wherein said aryl groups may be substituted by one to threehalogen, alkyl of 1 to 8 carbon atoms, alkoxy of 1 to 8 carbon atoms orcombinations thereof.

[0102] A preferred structure of formula (III) is where G₁ and G₂ areindependently benzyl or substituted benzyl. It is also possible for eachof G₁, G₂, and G₃ to be the same residue. G₁ and G₂ are also preferablyalkyl groups of 8 to 26 carbon atoms and most preferably alkyl groups of10 to 26 carbon atoms and G₃ is preferably an alkyl group of 1 to 22carbon atoms and most preferably methyl or substituted methyl. Also,preferred amine oxides include those wherein G₁, G₂, and G₃ are the samealkyl groups of 6 to 36 carbon atoms. Preferably, all of theaforementioned residues for G₆, G₂, and G₃ are saturated hydrocarbonresidues or saturated hydrocarbon residues containing at least one ofthe aforementioned —O—, —S—, —SO—, —CO₂—, —CO—, or —CON— moieties. Thoseskilled in the art will be able to envision other useful residues foreach of G₁, G₂, and G₃ without detracting from the present invention.

[0103] The saturated amine oxides of component ii.) may also includespoly(amine oxides). By poly(amine oxide) is meant tertiary amine oxidescontaining at least two tertiary amine oxides per molecule. Illustrativepoly(amine oxides), also called “poly(tertiary amine oxides)”, includethe tertiary amine oxide analogues of aliphatic and alicyclic diaminessuch as, for example, 1,4-diaminobutane; 1,6-diaminohexane;1,10-diaminodecane; and 1,4-diaminocyclohexane, and aromatic baseddiamines such as, for example, diamino anthraquinones anddiaminoanisoles.

[0104] Also included as component ii.) are tertiary amine oxides derivedfrom oligomers and polymers of the aforementioned diamines. Useful amineoxides also include amine oxides attached to polymers, for example,polyolefins, polyacrylates, polyesters, polyamides, polystyrenes, andthe like. When the amine oxide is attached to a polymer, the averagenumber of amine oxides per polymer can vary widely as not all polymerchains need to contain an amine oxide. All of the aforementioned amineoxides may optionally contain at least one —O—, —S—, —SO—, —CO₂—, —CO—,or —CONG₄— moiety. In a preferred embodiment, each tertiary amine oxideof the polymeric tertiary amine oxide contains a C₁ residue.

[0105] The groups G₁, G₂ and G₃ of formula (III) may be attached to amolecule containing a hindered amine. Hindered amines are known in theart and the amine oxide of the present invention may be attached to thehindered amine in any manner and structural position of the hinderedamine. Useful hindered amines when part of a compound of component ii.)include those of the general formulas (IV) and (V):

[0106] wherein L and R_(x) are as described above. Also included areamine oxides containing more than one hindered amine and more than onesaturated amine oxide per molecule. The hindered amine may be attachedto a poly(tertiary amine oxide) or attached to a polymeric substrate, asdiscussed above.

[0107] The compounds of component (b) are preferably used in amounts, intotal, of about 0.0005% to about 5%, in particular from about 0.001% toabout 2%, typically from about 0.01% to about 2% by weight, based on theweight of the polyolefin hollow article to be stabilized.

[0108] Component (c) employed in the novel process is at least onecompound that contains at least one group of the formula (VI)

[0109] in which R_(x) is hydrogen or methyl. Preferably R_(x) ishydrogen. Preferably, compounds of component (c) are of high molecularweight and may be discrete compounds or oligomeric mixtures.

[0110] Particularly preferred hindered amines of component (c) are:

[0111] The compounds of the sterically hindered amine type, are knownand some are commercially available.

[0112] Tinuvin® and Chimassorb® are protected trade names of CibaSpecialty Chemicals Corp. Sanduvor® and Hostavin® are protected tradenames of Clariant. Cyasorb® is a protected trade name of CytecCorporation. Uvinul® is a protected trade name of BASF. Uvasil® is aprotected trade name of Enichem. Uvasorb® is a protected trade name of3V Sigma.

[0113] The hindered amines of component (c) are preferably used inamounts of about 0.01% to about 10%, in particular from about 0.05% toabout 5%, typically from about 0.1% to about 3% by weight, based on theweight of the polyolefin hollow article to be stabilized.

[0114] The stabilizer combination comprising components (a), (b) and (c)is suitable for stabilizing polyolefin hollow articles which areprepared by the rotomolding process.

[0115] Examples for polyolefins are:

[0116] 1. Polymers of monoolefins and diolefins, for examplepolypropylene, polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene,polyisoprene or polybutadiene, as well as polymers of cycloolefins, forinstance of cyclopentene or norbomene, polyethylene (which optionallycan be crosslinked), for example high density polyethylene (HDPE), highdensity and high molecular weight polyethylene (HDPE-HMW), high densityand ultrahigh molecular weight polyethylene (HDPE-URMW), medium densitypolyethylene (MDPE), low density polyethylene (LDPE), linear low densitypolyethylene (LLDPE), (VLDPE) and (ULDPE).

[0117] Polyolefins, i.e. the polymers of monoolefins exemplified in thepreceding paragraph, preferably polyethylene and polypropylene, can beprepared by different, and especially by the following, methods:

[0118] i) radical polymerisation (normally under high pressure and atelevated temperature).

[0119] ii) catalytic polymerisation using a catalyst that normallycontains one or more than one metal of groups IVb, Vb, VIb or VIII ofthe Periodic Table. These metals usually have one or more than oneligand, typically oxides, halides, alcoholates, esters, ethers, amines,alkyls, alkenyls and/or aryls that may be either p- or s-coordinated.These metal complexes may be in the free form or fixed on substrates,typically on activated magnesium chloride, titanium(III) chloride,alumina or silicon oxide. These catalysts may be soluble or insoluble inthe polymerisation medium. The catalysts can be used by themselves inthe polymerisation or further activators may be used, typically metalalkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metalalkyloxanes, said metals being elements of groups Ia, IIa and/or IIIa ofthe Periodic Table. The activators may be modified conveniently withfurther ester, ether, amine or silyl ether groups. These catalystsystems are usually termed Phillips, Standard Oil Indiana, Ziegler(-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).

[0120] 2. Mixtures of the polymers mentioned under 1.), for examplemixtures of polypropylene with polyisobutylene, polypropylene withpolyethylene (for example PP/HDPE, PP/LDPE) and mixtures of differenttypes of polyethylene (for example LDPE/HDPE).

[0121] 3. Copolymers of monoolefins and diolefins with each other orwith other vinyl monomers, for example ethylene/propylene copolymers,linear low density polyethylene (LLDPE) and mixtures thereof with lowdensity polyethylene (LDPE), propylene/but-1-ene copolymers,propylene/isobutylene copolymers, ethylene/but-1-ene copolymers,ethylene/hexene copolymers, ethylene/methylpentene copolymers,ethylene/heptene copolymers, ethylene/octene copolymers,propylene/butadiene copolymers, isobutylene/isoprene copolymers,ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylatecopolymers, ethylene/vinyl ace tate copolymers and their copolymers withcarbon monoxide or ethylene/acrylic acid copolymers and their salts(ionomers) as well as terpolymers of ethylene with propylene and a dienesuch as hexadiene, dicyclopentadiene or ethylidene-norbomene; andmixtures of such copolymers with one another and with polymers mentionedin 1) above, for example polypropylene/ethylene-propylene copolymers,LDPE/ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acidcopolymers (EAA), LLDPE/EVA, LLDPE/EAA and alternating or randompolyalkylene/carbon monoxide copolymers and mixtures thereof with otherpolymers, for example polyamides.

[0122] Preferred polyolefins are polyethylene or polypropylene and theircopolymers with mono- and diolefin.

[0123] In addition to components (a), (b) and (c) the novel process maycomprise further costabilizers (additives) such as, for example, thefollowing:

[0124] 1. Antioxidants

[0125] 1.1. Alkylated monotphenols, for example2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl4,6-dimethylphenol,2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol,2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol,2-(α-methylcyclohexyl)-4,6-dimethylphenol,2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,2,6-di-tert-buty-4-methoxymethylphenol, nonylphenols which are linear orbranched in the side chains, for example, 2,6-di-nonyl-4-methylphenol,2,4-dimethyl-6-( 1 ′-methylundec-1 ′-yl)phenol,2,4-dimethyl-6′-(1′-methylheptadec-1′-yl)phenol,2,4-dimethyl-6-(1′-methyltridec-1′-yl)phenol and mixtures thereof.

[0126] 1.2. Alkylthiomethylphenols, for example2,4-dioctylthiomethyl-6-tert-butylphenol,2,4-dioctylthiomethyl-6-methylphenol,2,4-dioctylthiomethyl-6-ethylphenol,2,6-di-decylthiomethyl4-nonylphenol.

[0127] 1.3. Hydroquinones and alkylated hydroquinones, for example2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone,2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol,2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole,3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenylstearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

[0128] 1.4. Tocopherols, for example α-tocopherol, β-tocopherol,β-tocopherol, δ-tocopherol and mixtures thereof (Vitamin E).

[0129] 1.5. Hyroxylated thiodiphenyl ethers, for example2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol),4,4′-thiobis(6-tert-butyl-3-methylphenol),4,4′-thiobis(6-tert-butyl-2-methylphenol),4,4′-thiobis-(3,6-di-sec-amylphenol),4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.

[0130] 1.6. Alylidenebisphenols, for example2,2′-methylenebis(6-tert-butyl-4-metylphenol),2,2′-methylenebis(6-tert-butyl-4-ethylphenol),2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol],2,2′-methylenebis(4-methyl-6-cyclohexylphenol),2,2′-methylenebis(6-nonyl-4-methylphenol),2,2′-methylenebis(4,6-di-tert-butylphenol),2,2′-ethylidenebis(4,6-di-tert-butylphenol), 2,240-ethylidenebis(6-tert-butyl-4-isobutylphenol),2,2′-methylenebis[6-(α-methylbenzyl)-4-nonylphenol],2,2′-methylenebis[6-(α,α-dimethylbenzyl)4-nonylphenol],4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-methylenebis(6-tert-butyl-2-methylphenol),1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)4-methylphenol,1,1,3-tris(5-tert-butyl4-hydroxy-2-methylphenyl)butane,1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane,ethylene glycol bis[3,3-bis(3′-tert-butyl-4′-hydroxyphenyl)butyrate],bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene,bis[2-(3′-tert-butyl-2′-hydroxy-5′-methylbenzyl)-6-tert-butyl4-methylphenyl]terephthalate,11-bis-(3,5-dimethyl-2-hydroxyphenyl)butane,2,2-bis-(3,5-di-tert-butyl4-hydroxyphenyl)propane,2,2-bis-(5tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane,1,1,5,5-tetra-(5-tert-butyl4-hydroxy-2-methylphenyl)pentane.

[0131] 1.7. O-, N- and S-benzyl compounds, for example3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxy-dibenzyl ether,octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate,tridecyl4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate,tris(3,5-di-tert-butyl4-hydroxybenzyl)amine,bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate,bis(3,5-di-tert-butyl4-hydroxybenzyl)sulfide,isooctyl-3,5-di-tert-butyl4-hydroxybenzylmercaptoacetate.

[0132] 1.8. Hydroxybenzylated malonates, for exampledioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl) malonate,di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl) malonate,didodecylmercaptoethyl-2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

[0133] 1.9. Aromatic hydroxybenzyl compounds, for example1,3,5-tris-(3,5-di-tert-butyl4-hydroxybenzyl)-2,4,6-trimethylbenzene,1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

[0134] 1.10. Triazine Compounds for example2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,2-octylmercapto-4,6-bis(3,5-di-tert-butyl4-hydroxyphenoxy)-1,3,5-triazine,2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine,1,3,5-tris-(3,5-di-tert-butyl-hydroxy-4-benzyl)isocyanurate,1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine,1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine,1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

[0135] 1.11. Benzylphosphonates, for exampledimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate,diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate,dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, thecalcium salt of the monoethyl ester of3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

[0136] 1.12. Acylaminophenols, for example 4-hydroxylauranilide,4-hydroxystearanilide, octylN-(3,5-di-tert-butyl4-hydroxyphenyl)carbamate.

[0137] 1.13. Esters of β-(3,5-di-tert-butyl4-hydroxyphenyl)propionicacid with mono- or polyhydric alcohols, e.g. with methanol, ethanol,n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethyleneglycol, diethylene glycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl) isocyanurate, N,N′-bis(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0138] 1.14. Esters ofβ-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- orpolyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol,octadecanol, 1,6-hexane-diol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol,3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0139] 1.15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionicacid with mono- or polyhydric alcohols, e.g. with methanol, ethanol,octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0140] 1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acidwith mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol,octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethyleneglycol, triethylene glycol, pentaerythritol,tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,trimethylolpropane,4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0141] 1.17. Amides of β-(3.5-di-tert-butyl4-hydroxyphenyl)proionic acide.g.N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide,N,N′-bis(3,5-di-tert-butyl4-hydroxyphenylpropionyl)trimethylenediamide,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide,N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide(Naugard® XL-1 supplied by Uniroyal).

[0142] 1.18. Ascorbic acid (vitamin C)

[0143] 1.19. Aminic antioxidants, for exampleN,N′-di-isopropyl-p-phenylenediamine,N,N′-di-sec-butyl-p-phenylenediamine,N,N′-bis(1,4dimethylpentyl)-p-phenylenediamine, N,N′-bis(l-ethyl-3-methylpentyl)-p-phenylenediamine,N,N′-bis(1-methylheptyl)-p-phenylenediamine,N,N′-dicyclohexyl-p-phenylenediamine, N,N′-diphenyl-p-phenylenediamine,N,N′-bis(2-naphthyl)-p-phenylenediamine,N-isopropyl-N′-phenyl-p-phenylenediamine,N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine,N-cyclohexyl-N′-phenyl-p-phenylenediamine,4-(p-toluenesulfamoyl)diphenylamine,N,N′-dimethyl-N,N′-di-sec-butyl-p-phenylenediamine, diphenylamine,N-allyldiphenylamine, 4-isopropoxydiphenylamine,N-phenyl-1-naphthylamine, N-(4-tert-octylphenyl)-1-naphthylamine,N-phenyl-2-naphthylamine, octylated diphenylamine, for examplep,p′-di-tert-octyldiphenylamine, 4-n-butylaminophenol,4-butyrylaninophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol,4-octadecanoylaminophenol, bis(4-methoxyphenyl)amine,2,6-di-tert-butyl-4-dimethylaminomethylphenol,2,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethane,1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane,(o-tolyl)biguanide, bis[4-(1′, 3′-dimethylbutyl)phenyl]amine,tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- anddialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- anddialkylated nonyldiphenylamines, a mixture of mono- and dialkylateddodecyldiphenylamines, a mixture of mono- and dialkylatedisopropyl/isohexyldiphenylamines, a mixture of mono- and dialkylatedtert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine,phenothiazine, a mixture of mono- and dialkylatedtert-butyl/tert-octylphenothiazines, a mixture of mono- and dialkylatedtert-octyl-phenothiazines, N-allylphenothiazin,N,N,N′,N′-tetraphenyl-1,4-diaminobut-2-ene,N,N-bis(2,2,6,6-tetramethylpiperid-4-yl-hexamethylenediamine,bis(2,2,6,6-tetramethylpiperid-4-yl) sebacate,2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol.

[0144] 2. UV absorbers and light stabilizers

[0145] 2.1. 2-(2′-Hydroxyphenyl)benzotriazoles, for example2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)benzotriazole,2-(5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,2-(2′-hydroxy-5′-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-methylphenyl)-5-chloro-benzotriazole,2-(3′-sec-butyl-5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,2-(2′-hydroxy4′-octyloxyphenyl)benzotriazole, 2-(3′,5′-di-tert-amyl-2′-hydroxyphenyl)benzotriazole, 2-(3′,5′-bis-(α,α-dimethylbenzyl)-2′-hydroxyphenyl)benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole,2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)-carbonylethyl]-2′-hydroxyphenyl)-5-chloro-benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)benzotriazole,2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)benzotriazole,2-(3′-dodecyl-2′-hydroxy-5′-methylphenyl)benzotriazole, 2-(3′-tert-butyl-2′-hydroxy-5′-(2-isooctyloxycarbonylethyl)phenylbenzotriazole,2,2′-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol];the transesterification product of2-[3′-tert-butyl-5′-(2-methoxycarbonylethyl)-2′-hydroxyphenyl]-2H-benzotriazolewith polyethylene glycol 300; [R—CH₂CH₂—COO—CH₂CH₂₂ whereR=3′-tert-butyl-4′-hydroxy-5′-2H-benzotriazol-2-ylphenyl,2-[2′-hydroxy-3′-(α,α-dimethylbenzyl)-5′-(1,1,3,3-tetramethylbutyl)-phenyl]benzotriazole;2-[2′-hydroxy-3′-(1,1,3,3-tetramethylbutyl)-5′-(α,α-dimethylbenzyl)-phenyl]benzotriazole.

[0146] 2.2. 2-Hydroxybenzophenones, for example the 4-hydroxy,4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy,4,2′,4′-trihydroxy and 2′-hydroxy-4,4′-dimethoxy derivatives.

[0147] 2.3. Esters of substituted and unsubstituted benzoic acids, asfor example 4-tertbutyl-phenyl salicylate, phenyl salicylate,octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl)resorcinol, benzoyl resorcinol, 2,4-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate.

[0148] 2.4. Acrylates, for example ethyl α-cyano-β,β-diphenylacrylate,isooctyl α-cyano-β,β-diphenylacrylate, methyl α-carbomethoxycinnamate,methyl α-cyano-β-methyl-p-methoxy-cinnamate, butylα-cyano-β-methyl-p-methoxy-cinnamate, methylα-carbomethoxy-p-methoxycinnamate andN-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline.

[0149] 2.5. Nickel compounds, for example nickel complexes of2,2′-thio-bis-[4-(1,1,3,3-tetramethylbutyl)phenol], such as the 1:1 or1:2 complex, with or without additional ligands such as n-butylamine,triethanolamine or N-cyclohexyldiethanolamine, nickeldibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. themethyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzylphosphonicacid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenylundecylketoxime, nickel complexes of1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additionalligands.

[0150] 2.6. Oxamides, for example 4,4′-dioctyloxyoxanilide,2,2′-diethoxyoxanilide, 2,2′-dioctyloxy-5,5′-di-tert-butoxanilide,2,2′-didodecyloxy-5,5′-di-tert-butoxanilide, 2-ethoxy-2′-ethyloxanilide,N,N′-bis(3-dimethylaminopropyl)oxamide,2-ethoxy-5-tert-butyl-2′-ethoxanilide and its mixture with2-ethoxy-2′-ethyl-5,4′-di-tert-butoxanilide, mixtures of o- andp-methoxy-disubstituted oxanilides and mixtures of o- andp-ethoxy-disubstituted oxanilides.

[0151] 2.7. 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-(2,4-dihydroxyphenyl)4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine,2-(2-hydroxy4-octyloxyphenyl)4,6-bis(4-methylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-dodecyloxyphenyl)4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-tridecyloxyphenyl)4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[2-hydroxy4(2-hydroxy-3-butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine,2-[2-hydroxy4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]4,6-bis(2,4-dimethyl)-1,3,5-triazine,2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxy-phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[2-hydroxy4-(2-hydroxy-3-dodecyloxy-propoxy)phenyl]4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine,2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine,2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxy-propoxy)phenyl]-1,3,5-triazine,2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine,2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine.

[0152] 3. Metal deactivators, for example N,N′-diphenyloxamide,N-salicylal-N′-salicyloyl hydrazine, N,N′-bis(salicyloyl) hydrazine,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine,3-salicyloylamino-1.2,4-triazole, bis(benzylidene)oxalyl dihydrazide,oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide,N,N′-diacetyladipoyl dihydrazide, N,N′-bis(salicyloyl)oxalyldihydrazide, N,N′-bis(salicyloyl)thiopropionyl dihydrazide.

[0153] 4. Nitrones, for example, N-benzyl-alpha-phenyl-nitrone,N-ethyl-alpha-methyl-nitrone, N-octyl-alpha-heptyl-nitrone,N-lauryl-alpha-undecyl-nitrone, N-tetradecyl-alpha-tridecyl-nitrone,N-hexadecyl-alpha-pentadecyl-nitrone,N-octadecyl-alpha-heptadecyl-nitrone,N-hexadecyl-alpha-heptadecyl-nitrone,N-ocatadecyl-alpha-pentadecyl-nitrone,N-heptadecyl-alpha-heptadecyl-nitrone,N-octadecyl-alpha-hexadecyl-nitrone, nitrone derived fromN,N-di(hydrogenated tallow)hydroxylamine.

[0154] 5. Thiosynergists, for example, dilauryl thiodipropionate ordistearyl thiodipropionate.

[0155] 6. Peroxide scavengers, for example esters of β-thiodipropionicacid, for example the lauryl, stearyl, myristyl or tridecyl esters,mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zincdibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritoltetrakis(β-dodecylmercapto)propionate.

[0156] 7. Basic co-stabilizers, for example, melamine,polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, ureaderivatives, hydrazine derivatives, amines, polyamides, polyurethanes,alkali metal salts and alkaline earth metal salts of higher fatty acidsfor example calcium stearate, zinc stearate, magnesium behenate,magnesium stearate, sodium ricinoleate and potassium palmitate, antimonypyrocatecholate or zinc pyrocatecholate.

[0157] 8. Nucleating agents, for example, inorganic substances such astalcum, metal oxides such as titanium dioxide or magnesium oxide,phosphates, carbonates or sulfates of, preferably, alkaline earthmetals; organic compounds such as mono- or polycarboxylic acids and thesalts thereof, e.g. 4-tert-butylbenzoic acid, adipic acid,diphenylacetic acid, sodium succinate or sodium benzoate; polymericcompounds such as ionic copolymers (ionomers).

[0158] 9. Fillers and reinforcing agents, for example, calciumcarbonate, silicates, glass fibres, glass bulbs, asbestos, talc, kaolin,mica, barium sulfate, metal oxides and hydroxides, carbon black,graphite, wood flour and flours or fibers of other natural products,synthetic fibers.

[0159] 10. Benzofuranones and indolinones, for example those disclosedin U.S. Pat. Nos. 4,325,863; 4,338,244; 5,175,312; 5,216,052; 5,252,643;5,369,159; 5,488,117; 5,356,966; 5,367,008; 5,428,162; 5,428,177;5,516,920; DE-A-4316611; DE-A-4316622; DE-A4316876; EP-A-0589839 orEP-A-0591102or3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one,5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one,3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one],5,7-di-tert-butyl-3-(4hoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

[0160] 11. Other additives, for example, plasticisers, lubricants,emulsifiers, pigments, rheology additives, catalysts, flow-controlagents, optical brighteners, flameproofing agents, antistatic agents,clarifying agents and blowing agents.

[0161] The costabilizers are added, for example, in concentrations offrom about 0.01% to about 10% by weight, based on the overall weight ofthe polyolefin to be stabilized.

[0162] The fillers and reinforcing agents (item 9 in the list), forexample talc, calcium carbonate, mica or kaolin, are added to thepolyolefins in concentrations of about 0.01% to about 40% by weight,based on the overall weight of the polyolefins to be stabilized.

[0163] The fillers and reinforcing agents (item 9 in the list), forexample metal hydroxides, especially aluminium hydroxide or magnesiumhydroxide, are added to the polyolefins in concentrations of about 0.01%to about 60% by weight, based on the overall weight of the polyolefinsto be stabilized.

[0164] Carbon black as filler is added to the polyolefins inconcentrations, judiciously, of from about 0.01% to about 5% by weight,based on the overall weight of the polyolefins to be stabilized.

[0165] Glass fibers as reinforcing agents are added to the polyolefinsin concentrations, judiciously, of from about 0.01% to about 20% byweight, based on the overall weight of the polyolefins to be stabilized.

[0166] Preferred is a process comprising in addition to components (a),(b) and (c) further additives as well, especially phenolic antioxidants,light stabilizers or processing stabilizers.

[0167] Especially preferred additional additives are phenolicantioxidants (items 1.1 to 1.17 in the list) and peroxide scavengers(item 6 in the list).

[0168] The incorporation of components (a), (b) and (c) and optionalfurther additives into the polyolefin is carried out by known methods,for example before or after molding or also by applying the dissolved ordispersed stabilizer mixture to the polyolefin, with or withoutsubsequent evaporation of the solvent. The stabilizer mixture ofcomponents (a),-(b.) and (c) and optional further additives can also beadded to the polyolefins to be stabilized in the form of a masterbatchwhich contains these components in a concentration of, for example,about 2.5% to about 25% by weight.

[0169] Components (a), (b) and (c) and optional further additives canalso be added before or during the polymerization or beforecrosslinking.

[0170] Components (a), (b) and (c) and optional further additives can beincorporated into the polyolefin to be stabilized in pure form orencapsulated in waxes, oils or polymers.

[0171] Components (a), (b) and (c) and optional further additives canalso be sprayed onto the polyolefin to be stabilized. They are able todilute other additives (for example the conventional additives indicatedabove) or their melts so that they can be sprayed also together withthese additives onto the polyolefin to be stabilized. Addition byspraying during the deactivation of the polymerization catalysts isparticularly advantageous, it being possible to carry out sprayingusing, for example, the steam used for deactivation.

[0172] In the case of spherically polymerized polyolefins it may, forexample, be advantageous to apply components (a), (b) and (c),optionally together with other additives, by spraying.

[0173] During the rotomolding process, the temperature expedientlyreaches the range from about 200° C. to 400° C., preferably from about280° C. to 400° C., for example from about 310°C. to 400° C.

[0174] A preferred embodiment of this invention relates to the use ofthe stabilizer combination comprising components (a), (b) and (c) forpolyolefins processed by the rotomolding process.

[0175] The following Examples illustrate the invention in more detail.They are not to be construed as limiting the instant invention in anymanner whatsoever. The invention is declared to cover all changes andmodifications of the specific examples which do not constitute departurefrom the spirit and scope of the invention. Parts and percentages are byweight.

EXAMPLE 1 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0176] 100 parts medium density polyethylene, copolymerized with hexene(Novapol® TR-0735, nominal melt index 6.8 g/10 min., density 0.935g/cm³) are dry blended with 0.050 parts of calcium stearate and acombination of additional stabilizers (see below). The mixtures are meltcompounded into pellets at 232° C. in a Superior/MPM extruder using a24:1 L/D screw with Maddock mixing head at 100 rpm.

[0177] The compounded pellets are ground to a uniform particle size(150-500 μm) prior to the rotational molding process. This grinding stepincreases the surface area of the particles leading to a faster heatabsorption, and thus reducing overall energy consumption.

[0178] The rotational molding process is performed in a laboratory scaleequipment FSP M20 “Clamshell”. The ground resin is placed in a castaluminum mold, which is rotated biaxially in a gas fired oven. Hot airis circulated by blowers in the chamber while the temperature isincreased to 288° C. within 4 minutes. This temperature is maintainedfor a specific time (see Tables below). Subsequently, the oven is openedand while still rotating, the mold is cooled with forced air circulationfor 7 minutes, followed by water spray mist for 7 minutes, and anadditional air cooling step for 2 minutes. Throughout the entire heatingand cooling cycles, the speed of the major axis is maintained at 6 rpmwith a 4.5:1 ratio of rotation. After the cooling cycles, the mold isopened and the hollow object removed.

[0179] Formulation A is additionally blended with a combination of 0.100parts of the phosphite process stabilizer Irgafos® 168, 0.050 parts ofthe primary antioxidant Irganox® 1076 and 0.200 parts of the light andheat stabilizer Tinuvin® 783.

[0180] Formulation B is additionally blended with a combination of 0.100parts of the phosphite process stabilizer Irgafos® 168, 0.050 parts ofthe hydroxylamine process stabilizer Irgastab® 042 and 0.200 parts ofthe light and heat stabilizer Tinuvin® 783.

[0181] Formulation C is additionally blended with a combination of 0.100parts of the phosphonite process stabilizer Irgafos® P-EPQ, 0.050 partsof the hydroxylamine process stabilizer Irgastab® 042 and 0.200 parts ofthe light and heat stabilizer Tinuvin® 783.

[0182] Formulation D is additionally blended with a combination of 0.100parts of the phosphite process stabilizer Ultranox® 626, 0.050 parts ofthe hydroxylamine process stabilizer Irgastab® 042 and 0.200 parts ofthe light and heat stabilizer Tinuvin® 783.

[0183] Irgafos® 168 is tris-(2,4-di-tert-butylphenyl)phosphite.Ultranox® 626 is bis(2,4-di-tert-butylphenyl)pentaerythritoldiphosphite. Irgafos® P-EPQ istetrakis(2,4di-tert-butylphenyl)4,4′-biphenylene-diphosphonite.Irgastab® 042 is the N,N-di(alkyl)hydroxylamine produced by theN,N-di(hydrogenated tallow)amine. Tinuvin® 783 is a combination ofhindered amines of formulae (H4) and (H5). Irganox® 1076 is octadecyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Tinuvin®, Irgafos®,Irgastab® and Irganox® are registered trademarks of Ciba SpecialtyChemicals Corporation. Ultranox® is a registered trademark of GEChemicals.

[0184] Formulations A-D are rotationally molded into hollow objectsaccording to the general procedure with hold times of 6 to 14 minutes.

[0185] Yellowness Index of the outer surface is determined on a DCISF600 spectrophotometer according to ASTM D 1925. An increase inyellowness corresponds to a positive increase in the Yellowness Index.Formulations B-D are far superior to the comparative standardFormulation A with regard to color stability at these processingconditions. The results are reported in Table 1. TABLE 1 YellownessIndex Time Held Formulation at 288° C. (min.) A B C D  6 −2.13 −3.80−3.49 −3.00  8 −1.72 −4.08 −3.86 −3.30 10 −0.10 −1.86 −2.63 −2.70 129.58 0.96 −0.15 −0.46 14 8.00 3.14 5.28 1.40

[0186] Low-temperature impact strength testing is performed with aninstrumented drop weight (11.34 kg/50.8 cm) impact apparatus Dynatup®8250. Test specimens are conditioned in an air circulated freezer for noless than 12 hours at −40° C. prior to test.

[0187] The impact strength results, reported in % brittleness, are foundin Table 2. Formulation B proves to be superior to the comparativestandard Formulation A with regard to the failure mode based onlow-temperature impact strength testing at these processing conditions.TABLE 2 Impact Strength (% brittleness) Time Held at 288° C. (min.)Formulation A Formulation B  6  0 0  8 20 0 10 20 0 12 100  100 

[0188] The stabilizer mixtures of the present invention (FormulationsB-D) are superior compared to the state-of-the-art stabilizer mixture(Formulation A) for the prevention of color formation and for providingstability of polyolefin hollow articles produced by the rotomoldingprocess.

EXAMPLE 2 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0189] Hollow articles are prepared as per Example 1, replacing Tinuvin®783 of Formulation B with each of the following hindered aminestabilizers:

[0190] Formulation E: Irgafos® 168, Irgastab® 042 and Tinuvin® 622(compound of formula (H4)).

[0191] Formulation F: Irgafos® 168, Irgastab® 042 and Chimassorb® 944(compound of formula (H5)).

[0192] Formulation G: Irgafos® 168, Irgastab® 042 and Chimassorb® 119(compound of formula (H9)).

[0193] Formulation H: Irgafos® 168, Irgastab® 042 and Tinuvin® 111 (amixture of compounds of formulae (H4) and (H9)).

[0194] Formulation I: Irgafos® 168, Irgastab® 042 and Chimassorb® 2020(compound of formula (H10)).

[0195] Formulation J: Irgafos® 168, Irgastab® 042 and Cyasorb® UV-3346(compound of formula (H12)).

[0196] Formulation K: Irgafos® 168, Irgastab® 042 and Cyasorb® UV-3529(compound of formula (H13)).

[0197] Formulation L: Irgafos® 168, Irgastab® 042 and Uvasorb® HA88(compound of formula (H17)).

[0198] Formulation M: Irgafos® 168, Irgastab® 042 and Tinuvin® 123(compound of formula (H1)).

[0199] Formulation N: Irgafos® 168, Irgastab® 042 and hindered aminecompound of formula (H11).

[0200] Formulation O: Irgafos® 168, Irgastab® 042 and Hostavin® N30(compound of formula (H14)).

[0201] Formulation P: Irgafos® 168, Irgastab® 042 and Uvinul® 5050H(compound of formula (H15)).

[0202] Formulation Q: Irgafos® 168, Irgastab® 042 and Uvasil® 299(compound of formula (H16)).

[0203] Formulation R: Irgafos® 168, Irgastab® 042 and Uvasorb® HA88(compound of formula (H17)).

[0204] Irgafos® 168 is tris(2,4-di-tert-butylphenyl)phosphite. Irgastab®042 is a di(alkyl)hydroxylamine produced by the direct oxidation ofN,N-di(hydrogenated tallow)amine. Irgafos®, Irgastab®, Tinuvin® andChimassorb® are protected trade names of Ciba Specialty ChemicalsCorporation. Cyasorb® is a protected trade name of Cytec Corporation.Hostavin® is a protected trade name of Clariant. Uvinul® is a protectedtrade name of BASF. Uvasil® is a protected trade name of Enichem.Uvasorb® is a protected trade name of 3V Signa.

[0205] The stabilizer mixtures of the present invention (FormulationsE-R) are superior compared to a state-of-the-art stabilizer mixture(Formulation A) for the prevention of color formation and for providingstability of polyolefin hollow articles produced by the rotomoldingprocess.

EXAMPLE 3 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0206] Hollow articles are prepared as per Example 1, replacingIrgastab® 042 with N,N-dibenzylhydroxylamine in Formulations B-D. Thestabilizer mixtures of the instant invention, comprising an organicphosphite or phosphonite, N,N-dibenzylhydroxylamine and Tinuvin® 783 aresuperior compared to a state-of-the-art stabilizer mixture (FormulationA) for the prevention of color formation and for providing stability ofpolyolefin hollow articles produced by the rotomolding process.

EXAMPLE 4 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0207] Hollow articles are prepared as per Example 1, replacing Irgafos®168 of Formulation B with the phosphite process stabilizer Irgafos® 38.

[0208] Irgafos® 38, available from Ciba Specialty Chemicals Corporation,is bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite.

[0209] The formulation of the present invention comprising Irgafos® 38is superior compared to a state-of-the-art stabilizer mixture(Formulation A) for the prevention of color formation and for providingstability of polyolefin hollow articles produced by the rotomoldingprocess.

EXAMPLE 5 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0210] Hollow articles are prepared as per Example 1, replacingIrgastab® 042 of Formulations B-D with the amine oxide Genox™ EP. Thestabilizer mixtures of the present invention, comprising an organicphosphite or phosphonite, Genox™ EP and Tinuvin® 783 are superiorcompared to a state-of-the-art stabilizer mixture (Formulation A) forthe prevention of color formation and for providing stability ofpolyolefin hollow articles produced by the rotomolding process.

[0211] Genox™ EP is a di(C₁₆-C₁₈)alkyl methyl amine oxide, CAS#204933-93-7, available from GE Specialty Chemicals.

EXAMPLE 6 Preparation of Polyolefin Hollow Articles by the RotomoldingProcess

[0212] Hollow articles are prepared as per Example 1, replacing Irgafos®168 and Irgastab® 042 of Formulation B with the phosphite processstabilizer Irgafos® 38 and the amine oxide Genox™ EP, respectively.

[0213] Irgafos® 38, available from Ciba Specialty Chemicals Corporation,is bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite. Genox™ EP is adi(C₁₆-C18)alkyl methyl amine oxide, CAS# 204933-93-7, available from GESpecialty Chemicals.

[0214] The formulation of the present invention comprising Irgafos® 38,Genox™ EP and Tinuvin® 783 is superior compared to a state-of-the-artstabilizer mixture (Formulation A) for the prevention of color formationand for providing stability of polyolefin hollow articles produced bythe rotomolding process.

What is claimed is
 1. A process for the production of polyolefin hollowarticles, which comprises charging the polyolefin with a stabilizercombination, comprising (a) at least one compound from the group of theorganic phosphites and phosphonites, (b) one or more compounds selectedfrom the group consisting of i.) hydroxylamine derivatives and ii.)amine oxide derivatives and (c) at least one compound from the group ofthe hindered amine stabilizers, filling this mixture into a mold,heating this mold in an oven to above 280° C., such that the stabilizedpolyolefin fuses, rotating the mold around at least 2 axes, the plasticmaterial spreading to the walls, cooling the mold while still rotating,opening it, and taking the resultant hollow article out.
 2. A processaccording to claim 1 wherein the organic phosphites and phosphonites ofcomponent (a) are selected from the group consisting of formulae (1),(2), (3), (4), (5), (6) and (7)

in which the indices are integral and n is 2, 3 or 4; p is 1 or 2; q is2 or 3; r is 4 to 12; y is 1, 2 or 3; and z is 1 to 6; A₁, if n is 2, isC₂-C₁₈ alkylene; C₂-C₁₂ alkylene interrupted by oxygen, sulfur or —NR₄—;a radical of the formula

 or phenylene; A₁, if n is 3, is a radical of the formula—C_(r)H_(2r-1)—; A₁, if n is 4, is

A₂ is as defined for A₁ if n is 2; B is a direct bond, —CH₂—, —CHR₄—,—CR₁R₄—, sulfur, C₅-C₇ cycloalkylidene, or cyclohexylidene which issubstituted by from 1 to 4 C₁-C₄ alkyl radicals in position 3, 4 and/or5; D₁, if p is 1, is C₁-C₄alkyl and, if p is 2, is —CH₂OCH₂—; D₂, if pis 1, is C₁-C₄ alkyl; E, if y is 1, is C₁-C₁₈ alkyl, —OR₁ or halogen; E,if y is 2, is —O—A₂—O—, E, if y is 3, is a radical of the formulaR₄C(CH₂O—)₃ or N(CH₂CH₂O—)₃; Q is the radical of an at least z-valentalcohol or phenol, this radical being attached via the oxygen atom tothe phosphorus atom; R₁, R₂ and R₃ independently of one another areC₁-C₁₈ alkyl which is unsubstituted or substituted by halogen, —COOR₄,—CN or —CONR₄R₄; C₂-C₁₈ alkyl interrupted by oxygen, sulfur or —NR₄—;C₇-C₉ phenylalkyl; C₅-C₁₂ cycloalkyl, phenyl or naphthyl; naphthyl orphenyl substituted by halogen, 1 to 3 alkyl radicals or alkoxy radicalshaving a total of 1 to 18 carbon atoms or by C₇-C₉ phenylalkyl; or aradical of the formula

 in which m is an integer from the range 3 to 6; R₄ is hydrogen, C₁-C₈alkyl, C₅-C₁₂ cycloalkyl or C₇-C₉ phenylalkyl, R₅ and R₆ independentlyof one another are hydrogen, C₁-C₈ alkyl or C₅-C₆ cycloalkyl, R₇ and R₈,if q is 2, independently of one another are C₁-C₄ alkyl or together area 2,3-dehydropentamethylene radical; and R₇ and R₈, if q is 3, aremethyl; R₁₄ is hydrogen, C₁-C₉ alkyl or cyclohexyl, R₁₅ is hydrogen ormethyl and, if two or more radicals R₁₄ and R₁₅ are present, theseradicals are identical or different, X and Y are each a direct bond oroxygen, Z is a direct bond, methylene, —C(R₁₆)₂— or sulfur, and R₁₆ isC₁-C₈ alkyl.
 3. A process according to claim 1 wherein the organicphosphites and phosphonites of component (a) are selected from the groupconsisting of tris(2,4-di-tert-butylphenyl) phosphite, tris(nonylphenyl)phosphite and formulae (A), (B), (C), (D), (E), (F), (G), (H), (J), (K)and (L)


4. A process according to claim 1 wherein the hydroxylamine derivativesof component (i) are of the formula (II)

wherein T₁ is straight or branched chain alkyl of 1 to 36 carbon atoms,cycloalkyl of 5 to 12 carbon atoms, aralkyl of 7 to 9 carbon atoms, orsaid aralkyl substituted by one or two alkyl of 1 to 12 carbon atoms orby one or two halogen atoms; T₂ is hydrogen, or independently has thesame meaning as T₁.
 5. A process according to claim 4 wherein T₁ and T₂are independently benzyl, ethyl, octyl, lauryl, dodecyl, tetradecyl,hexadecyl, heptadecyl or octadecyl.
 6. A process according to claim 1wherein the hydroxylamine derivatives of component (i) are selected fromthe group consisting of N,N-dibenzylhydroxylamine,N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine,N,N-dilaurylhydroxylamine, N,N-didodecylhydroxylamine,N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine,N,N-dioctadecylhydroxylamine, N-hexadecyl-N-tetradecylhydroxylamine,N-hexadecyl-N-heptadecylhydroxylamine,N-hexadecyl-N-octadecylhydroxylamine,N-heptadecyl-N-octadecylhydroxylamine, and N,N-di(hydrogenatedtallow)hydroxylamine.
 7. A process according to claim 1 whereincomponent (i) is an N,N-di(alkyl)hydroxylamine produced by the directoxidation of N,N-di(hydrogenated tallow)amine.
 8. A process according toclaim 1 wherein the amine oxide derivatives of component (ii) are of theformula (III)

wherein G₁ and G₂ are independently a straight or branched chain alkylof 6 to 36 carbon atoms, aryl of 6 to 12 carbon atoms, aralkyl of 7 to36 carbon atoms, alkaryl of 7 to 36 carbon atoms, cycloalkyl of 5 to 36carbon atoms, alkcycloalkyl of 6 to 36 carbon atoms or cycloalkylalkylof 6 to 36 carbon atoms; G₃ is a straight or branched chain alkyl of 1to 36 carbon atoms, aryl of 6 to 12 carbon atoms, aralkyl of 7 to 36carbon atoms, alkaryl of 7 to 36 carbon atoms, cycloalkyl of 5 to 36carbon atoms, alkcycloalkyl of 6 to 36 carbon atoms or cycloalkylalkylof 6 to 36 carbon atoms; with the proviso that at least one of G₁, G₂and G₃ contains a β carbon-hydrogen bond; and wherein said alkyl,aralkyl, alkaryl, cycloalkyl, alkcycloalkyl and cycloalkylalkyl groupsmay be interuppted by one to sixteen —O—, —S—, —SO—, —SO₂—, —COO—,—OCO—, —CO—, —NG₄—, —CONG₄— and —NG₄CO— groups, or wherein said alkyl,aralkyl, alkaryl, cycloalkyl, alkcycloalkyl and cycloalkylalkyl groupsmay be substituted by one to sixteen groups selected from —OG₄, —SG₄, —COOG₄, —OCOG₄, —COG₄, —N(G₄)₂, —CON(G₄)₂, —NG₄COG₄ and 5- and 6-memberedrings containing the —C(CH₃)(CH₂R_(x))NL(CH₂R_(x))(CH₃)C— group orwherein said alkyl, aralkyl, alkaryl, cycloalkyl, alkcycloalkyl andcycloalkylalkyl groups are both interuppted and substituted by thegroups mentioned above; and wherein G₄ is independently hydrogen oralkyl of 1 to 8 carbon atoms; R_(x) is hydrogen or methyl; L is a C₁₋₃₀straight or branched chain alkyl moiety, a —C(O)R moiety wherein R is aC₁₋₃₀ straight or branched chain alkyl group, or a —OR moiety wherein Ris a C₁₋₃₀ straight or branched chain alkyl group; and wherein said arylgroups may be substituted by one to three halogen, alkyl of 1 to 8carbon atoms, alkoxy of 1 to 8 carbon atoms or combinations thereof. 9.A process according to claim 8 wherein wherein G₁ and G₂ areindependently straight or branched chain alkyl groups of 6 to 22 carbonatoms and G₃ is a straight or branched chain alkyl of 1 to 22 carbonatoms.
 10. A process according to claim 8 in which G₃ is methyl.
 11. Aprocess according to claim 8 wherein G₁ and G₂ are each independently astraight or branched chain alkyl of 12 to 22 carbon atoms and wherein G₃is methyl.
 12. A process according to claim 8 wherein G₁, G₂ and G₃ areeach independently a straight or branched chain alkyl of 12 to 22 carbonatoms.
 13. A process according to claim 8 wherein the amine oxidederivatives of component (ii) are selected from the group consisting ofdidecyl methyl amine oxide, tridecyl amine oxide, tridodecyl amine oxideand trihexadecyl amine oxide.
 14. A process according to claim 8 whereinat least one of G₁, G₂ and G₃ comprises at least one moiety of the groupconsisting of —O—, —S—, —SO—, —COO—, —CO— and —CONG₄—.
 15. A processaccording to claim 1 wherein the amine oxide derivatives are poly(amineoxides).
 16. A process according to claim 15 wherein the poly(amineoxides) comprise at least one moiety of the group consisting of —O—,—S—, —SO—, —COO—, —CO— and —CONG₄—.
 17. A process according to claim 8wherein one or more of G₁, G₂ and G₃ is substituted by one to sixteengroups of formulae (IV) and (V),


18. A process according to claim 1 wherein the hindered aminestabilizers of component (c) contain at least one group of the formula(VI)

in which R_(x) is hydrogen or methyl.
 19. A process according to claim18 wherein the hindered amine stabilizers are selected from the groupconsisting of formulae (H1), (H2), (H3), (H4), (H5), (H6), (H7), (H8),(H9), (H10), (H11), (H12), (H13), (H14), (H15), (H16) and (H17)


20. A process according to claim 1, wherein the temperature reaches therange from about 200° C. to 400° C.